Percussion machine for fasteners

ABSTRACT

A PRECUSSION MACHINE FOR DRIVING FASTENING ELEMENTS SUCH AS NAILS, STAPLES, OR THE LIKE INTO WORKPIECES WHICH IS PROVIDED WITH DIFFERENT SAFETY MEANS AND ESPECIALLY WITH PREVENTING THE PRECUSSION PISTON WITH A STRIKER   ROD THERON FROM CARRYING OUT A DRIVING STROKE WHEN NO FASTENING ELEMENT IS LOCATED WITHIN THE GUIDE CHANNEL OF THE STRIKER ROD.

A. CAST ET AL PERCUSSION MACHINE FOR FASTENERS Sept. 20,1971

Filed March a, 1968 5 Sheets-Sheet 2 Inventors. IQDOLF 634.37 HE/NZ .s'cwwmez xum- E'lCH 77 fi7'70 E) v Sept. 20, 1971 A. CAST ETAL PERCUSSION MACHINE FOR FASTENERS Filed March 1968 S'Sheets-Sheet 5 Inventors. ADOLF CAST HE/NZ SCHW/QEZ KUR 7' 25/01 5 j 77 1477' NE) Sept. 20 1971 ETAL PERCUSSION mcnnm FOR FASTENERS s Sheets-Sheet 4 Filed March 5, 1968 Z s R r M w 9% n N m an mm; m DIEM DEV AHK W w Sept. 20, 1971 CAST ETAL r 3,606,128

f PERCUSSION MACHINE FOR FASTENERS Filed March 5, 1968 5 Sheets-Sheet s l I 54 E Q ,l 25 /7 &

Inventors. IDOLF c3457 HE/NZ .S'C'l/W/i/QZ KURT RE/CH 3,606,128 Patented Sept. 20, 1971 3,606,128 PERCUSSIGN MACHINE FOR FASTENERS Adolf Cast, Oberlenningen, Heinz Schwarz, Zizishausen,

and Kurt Reich, Nurtingen, Germany, assignors to Karl M. Reich, Maschinenfabrik, Nurtingen, Germany Filed Mar. 5, 1968, Ser'. No. 710,524 Claims priority, application Germany, Mar. 7, 1967, P 16 03 943.3 Int. Cl. B27f 7/06 U.S. Cl. 227-1 25 Claims ABSTRACT OF THE DISCLOSURE A percussion machine for driving fastening elements such as nails, staples, or the like into workpieces which is provided with different safety means, and especially with means for preventing the percussion piston with a striker rod thereon from carrying out a driving stroke when no fastening element is located within the guide channel of the striker rod.

The present invention relates to a percussion machine for driving fastening elements into workpieces which comprises a guide channel to which the fastening elements are supplied individually, a percussion piston which is adapted to be driven so as to exert one or more impacts upon each fastening element within the guide channel, and a control mechanism for manually controlling the operations of the ercussion piston.

Percussion machines of the general type as described above are known for a long time for many different purposes, for example, for driving large bolts, nails, pins, staples, or the like into workpieces. For driving the percussion pistons of these machines, various pressure means are employed, for example, compressed air, oil or the like, electromagnetic mean, or propellent gases which are generated by explosion. Some of these machines are designed so as to permit the fastening elements to be inserted individually through a feed line into the guide channel, while other machines of this type are provided with magazines containing the fastening elements in the form of a row which extends continuously from the magazine to the guide channel so that after one fastening element has been driven into a workpiece, the next fastening element will be fed into the guide channel as soon as the percussion piston has been retracted therefrom. The fastening elements within these rows may lie either loosely adjacent to each other or they may be attached to each other so as to form prefabricated strips which may then be inserted as a unit into the magazine.

All of these percussion machines have in common that the percussion piston must be driven with such a large energy that each fastening element may be driven completely into the workpiece by one or several impacts. This, however, has the serious disadvantage that, if for any reason no fastening element is located within the guide channel when the percussion piston carries out a driving stroke, the entire striking energy of the piston must be absorbed by a buffer which is mounted in the machine. This may occur especially in magazine-equipped percussion machines, for example, in a nailing machine when the magazine is empty of nails. The percussion piston may then even carry out numerous idle strokes before the operator of the machine will notice this since he has to devote his entire attention to the proper application of the machine upon the workpiece and cannot also watch that the magazine still contains a suflicient number of fastening elements so that idle strokes will be avoided. This disadvantage is especially serious in the use of percussion machines in which the completion of a driving stroke of the percussion piston upon one fastening element automatically initiates the next driving stroke so that all fastening elements which are contained, for example, in the magazine will be driven into a workpiece in a quick succession like the bullets of a machine gun. If the supply of fastening elements contained in the magazine of such a machine is consumed, the percussion piston may carry out a large series of idle strokes in.

rapid succession before the operator will notice that the su-pply of fastening elements is exhausted.

Especially because of the large frequency in which they may occur, these idle strokes will result in a premature destruction of the bulfer, the percussion piston, and the foot of the machine carrying the buffer. This result of the idle strokes is especially critical in percussion machines in which the driving strokes follow each other automatically.

It is the principal object of the present invention to provide a percussion machine of the type as first men tioned above which is designed so as at least to reduce considerably the disdvantageous effects of idle strokes of the percussion piston or to prevent the occurrence of idle strokes entirely.

According to the invention this object is attained by providing the percussion machine with a safety device which in its normal position prevents the driving stroke of the percussion piston and which by the presence of a fastening element within the guide channel is adapted to be moved to a releasing position in which it permits the full energy of the percussion piston to be released for driving the fastening element into a workpiece.

According to an embodiment of the invention, the safety device may consist of a control element which in its normal position prevents the actuation of the driving means of the percussion piston.

For determining whether or not the guide channel contains a fastening element, it is also possible to provide a variety of diiferent means. If the percussion machine is provided, for example, in the form of a magazine-equipped nailing or stapling machine wherein the magazine is adapted to hold a definite quantity of nails or staples the safety device may comprise, for example, a counter which is actuated whenever a nail or staple has been driven into a workpiece and which thus indicates the time when the contents of the magazine are exhausted. Such a counter may actuate a control mechanism which either slows down or stops the percussion piston or switches off the driving means of the percussion piston. In place of such a counter it is also possible, for example, in a magazineequipped percussion machine, to provide a device for indicating the present magazine contents, for example, in the form of a slide member for feeding the fastening elements into the guide channel. The indicating device may be designed so as to permit only one more fastening element to be driven into a workpiece when the last fastening element from the magazine has been inserted into the guide channel.

For determining the presence of a fastening element within the guide channel and for thereby moving the safety device to its releasing position, it is possible to provide either an electric, magnetic, pneumatic, or photometric control element. Thus, for example, according to one preferred embodiment of the invention, the safety device is provided with a feeler which in its neutral position engages into the guide channel and is movable by a fastening element which is located within the guide channel to its operative position in which it moves the safety device to its releasing position. This feeler may also be employed for operating any of the valves, brakes or the like as mentioned above which may serve as safety devices. It may, however, also be provided for operating a control element which prevents the actuation of the driving means of the percussion piston when the feeler is in its neutral position so that the driving means may be actuated only when the feeler has been moved to its operative position by a fastening element which is located within the guide channel. Such control elements which are. operatively associated with the driving means of the percussion piston, for example, of a pneumatically driven percussion machine, may consist, for example, of suitable valves or the like.

In some of the percussion machines of the general type as mentioned in the beginning it is already known to provide a contact feeler which when the machine is applied against a workpiece is moved from its neutral position to its operative position in which it permits the driving means of the percusson piston to be actuated. According to the present invention, a machine of this type may be designed so that, when the first-mentioned feeler or fastener feeler for determining the presence of a fastening element in the guide channel is in its neutral position, it prevents the contact feeler from acting upon the driving means of the percussion piston. This may be attained, for example, by designing the mechanism so that the fastener feeler when in its neutral position interrupts the connection between the contact feeler and the actuating device for the driving means, for example, by providing a connecting device which is adapted to connect the contact feeler to the actuating device and to be operated by the fastener feeler so that when this feeler is in its neutral position, the connecting device will be in the disconnecting position and when it is in its operative position, the connecting device will be in the connecting position. By these extremely simple means the result is attained that, when no fastening element is located in the guide channel, the connecting device will not connect the contact feeler to the actuating device so that the latter will be prevented from actuating the driving means. This has the advantage that the machine cannot carry out any idle strokes which applies not only to percussion machines in which the fastening elements are supplied individually through a feed line but also to machines with an automatic succession of driving strokes. In the latter machines, the driving means for the percussion piston will then be switched oif immediately as soon as the fastener feeler disengagcs the connecting device.

According to another advantageous embodiment of the invention, the percussion machine is provided with a locking device for the contact feeler which locks the contact feeler when the fastener feeler is in its neutral position and releases it when the fastener feeler is in its operative position. This has the advantage that, when no fastening element is present in the guide channel, the contact feeler will be locked by the locking device. Consequently, the contact feeler cannot be moved at all to the releasing position as long as no fastening element is located in the guide channel.

The present invention is of particular advantage also when applied to percussion machines in which the fastening elements are fed individually through a feed line into the guide channel. In these machines it may occasionally occur that a fastening element will be only partly inserted into the guide channel which may result in considerable trouble when the next driving stroke occurs. If such a machine is provided with the safety device according to the invention and more particularly with a suitable arrangement of the fastener feeler within the guide channel, such trouble may be entirely avoided since a full stroke of the percussion piston may then be carried out only if the fastening element is located in its proper position within the guide channel.

The features and advantages of the present invention will become further apparent from the following detailed description thereof which is to be read with reference to the accompanying drawings, in which FIG. 1 shows, partly in a longitudinal section, a side view of a percussion machine accordin to the invention in the form of a nailing machine;

FIG. 1a shows a cross section which is taken along the line I--I of FIG. 1;

FIG. 2 shows a view of a detail of the machine, as seen in the direction of the arrow II in FIG. 1;

FIG. 3 shows a perspective illustration of the locking engagement of the contact feeler of the nailing machine according to FIGS. 1 and 2 with a contact feeler at the lower end of the guide channel of the machine;

FIG. 4 shows a longitudinal section of a part of the nailing machine according to FIG. 1 with a nail inserted into the guide channel and in a position when the machine is not applied upon a workpiece;

FIG. 5 shows a similar view of the nailing machine according to FIG. 1 in the position when the machine is applied upon a workpiece and the contact feeler is pressed upwardly by the workpiece and a nail may be driven as soon as the trigger is pulled;

FIG. 6 shows a longitudinal section of the foot of a nailing machine according to a modification of the invention with a nail magazine thereon;

FIG. 7 shows a view which is taken in the direction of the arrow VII in FIG. 6;

FIG. 8 shows a cross section which is taken along the line VIIIVIII in FIG. 6;

FIG. 9 shows a view of a part of FIG. 6 with a nail inserted into the guide channel;

FIG. 10 shows a longitudinal section similar to FIG. 6 of a percussion machine in the form of a stapling machine with a staple magazine thereon;

FIG. 11 shows a cross section which is taken along the line XI--XI of FIG. 10;

FIG. 12. shows a view similar to FIG. 10, but with the contact feeler pressed upwardly by the workpiece;

FIG. 13 shows a part of the view according to FIG. 10, but with the parts of the stapling machine in the position when the magazine is empty;

FIG. 14 shows a view similar to the lower part of FIG. 1 of another modification of the nailing machine according to FIGS. 1 to 5;

FIG. 15 shows a cross section which is taken along the line XVXV of FIG. 14.

FIGS. 1 to 5 of the drawings illustrate a percussion machine in the form of a nailing machine which comprises a housing 1, a handle 2, and a foot 3. Housing 1 contains a working cylinder 4 with a pneumatically driven percussion piston 5 therein which is connected to the upper end of a rod-shaped striker 6 which is slidable within a guide channel 7 into the lower part of which nails 8 are fed pneumatically through a feed channel 9 which terminates into an aperture in the wall of foot 3.

The compressed air for carrying out the driving strokes of piston 5 and striker 6 is supplied to the machine through a hose 12. which is connected to a socket 11 on the handle 2 of the machine. For carrying out a driving stroke, the housing of the handle 2 contains a release valve 13 with a valve pin 14 which may be shifted against a resetting force to the stroke-releasing or operative position by an actuating lever 15 when a trigger 16 is pulled. In order to prevent such a driving stroke from being released when the machine is not applied against a workpiece, a contact feeler 17 is provided which normally projects from the front end of the foot 3 and is adapted to be pushed into the latter against the action of a spring, not shown, in a direction parallel to the axis of guide channel 7 when the foot 3 is pressed against a workpiece 18, as shown in FIG. 5, and until the foot 3 engages upon the Workpiece. This contact feeler 17 forms the front end of a flat rod 19 which is bent several times at different angles and the upper end 21 of which extends to a point adjacent to the valve pin 14 and carries the actuating lever 15 which is pivotable about an axis 22. This axis 22 is located in such a position that, when the foot 3 is not applied against a workpiece 18 and the feeler 17 is in its released position, the actuating lever will not engage with the valve pin 14 when the trigger 15 is pulled. Consequently, as long as the foot 3 is not pressed against a workpiece so that the feeler 17 will thereby be pushed upwardly, the actuation of the trigger 16 cannot result in a driving stroke of the piston 5 and striker 6. If, however, the foot 3 is pressed against a workpiece 18 and the feeler 17 together with rod 19 is pressed upwardly, the axis 22 of the actuating lever will be shifted to the position as shown in FIG. 5 so that, when the trigger 16 is then pulled, the valve pin 14 will be shifted and will thereby effect a driving stroke of piston 5.

In order to prevent a nail 8 when being fed pneumatically into the guide channel 7 from being shot out of the latter which may result in serious trouble, the outlet of the guide channel is provided with a nail stop 23 which in its normal position blocks the outlet of guide channel 7 so that, when a nail is shot into the guide channel, it will hit against this nail stop and cannot be shot out of the guide channel. This nail stop 23 projects laterally from the lower end of a lever 24 which is pivotable about an axis against the action of a torsion spring 25 from its normal or blocking position as shown in FIG. 1 to the position as shown in FIG. 5, in which it frees the outlet of guide channel 7. Lever 24 is for this purpose connected to the contact feeler 17 by a pin 26 which, as shown particularly in FIG. 3, is operatively associated with a detent on feeler 17 which has an outer edge 27 extending at an acute angle to the direction of movement of feeler 17 so that, when the latter is moved upwardly by the pressure of foot 3 against a workpiece, the inclined edge 27 will slide along pin 26 and thereby pivot the lever 24 against the action of spring 25 from its position as shown in FIG. 4 to the position as shown in FIG. 5, in which the nail stop 23 is pivoted laterally away from the outlet of guide channel 7.

Lever 24 is further provided with a nose which projects through a slot 28 in guide channel 7 and forms a nail feeler 29 which is adapted to determine whether or not a nail 8 is located within the guide channel 7. When a nail 8 is being inserted into guide channel 7, as shown in FIG. 4, this nail will push the feeler 29 laterally out of the guide channel so that the lever 24 will be pivoted from the position as shown in FIG. 1 to the position as shown in FIG. 4 in which, however, the nail stop 23 still covers the outlet of guide channel 7. The inclined edge 27 of the detent on the contact feeler T17 terminates at its upper end into a shoulder 31 which holds the pin 26 on lever 24 in a fixed position when the feeler 17 and lever 24 are in their normal positions. Pin 26 therefore forms a locking bolt which, by engaging with shoulder 31 when the lever 24 is in its normal position, locks the contact feeler 17 in its normal position and insures that, when guide channel 7 does not contain a nail and lever 24 is therefore in the position as shown in FIGS. 1 and 3, the contact feeler 17 cannot be pressed upwardly by a workpiece 18 when the foot 3 of the machine is pressed against the wonkpiece. This, in turn, means that the actuation of the trigger 16 also cannot effect a driving stroke of piston 5. If, however, a nail 8 is located in the proper position in guide channel 7, as illustrated in FIG. 4, lever 24 will be pivoted to the position as shown in FIG. 4 in which pin 26 is swung away from the shoulder 31 so that, when the foot 3 of the machine is then pressed against a workpiece 18, the contact feeler 17 will be pushed upwardly so that by means of the inclined edge 27 and pin 26 the lever 24 will be pivoted to the position as shown in FIG. 5 in which the nail stop 23- no longer covers the outlet of guide channel 7. At the same time, the axis 22 of the actuating lever 15 will be shifted to the position as shown in FIG. 5 so that, if the trigger 16 is then pulled, piston '5 will carry out a driving stroke.

The side of the foot 3 into which the nail feed line 9 terminates is provided with a slot 32 in which a lever 33 is pivotable about an axis 34 toward the outside of slot 32. The lower end of lever 33 forms a clamping jaw which is adapted to clamp the nail 8 which is inserted into the guide channel 7 in a fixed position. This clamping jaw 30 and the opposite wall portion of channel 7 define a constriction 10 of this channel which, as may be seen in FIG. la, has a prismatic shape. Above this constriction 10, the part of guide channel 7 into which a nail is fed from the feed channel 9 has likewise a prismatic shape but a larger cross section so that, due to the engagement of the head of nail 8 in guide channel 7 with the side of the latter opposite to the mouth of feed channel 9, the axis of the nail is laterally offset relative to the axis of the striker 6. The lateral inner surfaces of the foot 3 which define one side of the constriction 10 are designed so as to permit the striker 6 to enter into the constriction by sliding along these lateral surfaces.

For holding the-lever 33 in the position in which it closes the slot 32 and clamps the nail 8, a leaf spring 35 is provided the upper end of which is pivotably connected to the housing 1 so that this spring may pivot about an axis 36 extending at a right angle to the pivot axis 34 of lever 33. The lower end of leaf spring 35 which acts upon the lever 33 is bent so as to form an eye 37 which serves as a handle for pivoting the spring 35 laterally out of its position in which it engages upon the lever 33. The axis 34 of lever 33 is located near the upper end of the guide channel 7 so that, when lever 33 is pivoted out of the slot 32 after the leaf spring 35 has been pivoted away toward one lateral side thereof, guide channel 7 will be open toward one side so as to permit a nail which has been improperly inserted into the guide channel to be easily removed therefrom. This is especially important when the machine operates at a very high nailing speed so that, if any disorders occur, they can be remedied very quickly.

When during the driving stroke of piston 5, the head of the nail 8 and the striker 6 enters the constriction 10, they will press the clamping jaw 30 toward one side. At the same time, the side walls of the constriction 10 will shift the nail head laterally so that the longitudinal axis of the nail will be substantially in alignment with the axis of the striker 6. In order to prevent the wall surfaces of the constriction 10 which came in contact with the nail head and with the striker 6, and especially the surfaces on lever 33, from being worn, these surfaces may be provided with a coating of hard metal.

For preventing a premature fatigue of leaf spring 35 due to the fact that lever 33 might be thrown too far outwardly by the impact of the striker 6 during its driving strokes, the foot 3 is provided with a bracket 39 which encloses the slot 32 and forms a stop 40 which is provided on the inside with an elastic buffer 40'.

.For preventing the nail stop 23 from being damaged by the points of the nails when the latter are inserted into the guide channel 7, it is advisable to provide the nail stop 23 with an insert 23 of hard metal.

In order to insure that, when a nail 8 is being driven into a workpiece, the nail feeler 29 will be forced out of the guide channel 7 as smoothly as possible by the nailhead and then by the striker 6, the upper edge portion 38 of feeler 29 facing the striker 6 is inclined at an acute' angle to the axis of guide channel 7.

FIGS. 6 to 9 illustrate another embodiment of the invention in the form of a nailing machine which is equipped with a nail magazine. Since this machine is in many respects similar to the machine according to FIGS. 1 to 5, all those parts of the nailing machine according to FIGS. 6 to 9 the functions of which are similar to those of the parts of the machine as previously described are designated by numerals which are increased by over those applied in FIGS. 1 to 5. Insofar as these parts are concerned, reference is therefore made to the preceding description.

The foot 103 of the nailing machine according to FIGS. 6 to 9 is likewise provided with a contact feeler 117 which is movable in a direction parallel to the axis of the guide channel 107 and the upper part of which likewise consists of an angular rod 119. The upper end of this rod 119 likewise carries a pivotable actuating lever (not shown) similar to the lever 15 as shown in FIG. 1 which is operatively associated with a trigger 16 in the same manner as previously described.

The nailing machine according to FIGS. 6 to 9 is likewise provided with a locking device for the contact feeler 117 which comprises a lever 124 which is pivotable about an axis 120 and adapted to engage through a slot 128 in the foot 103 into the guide channel 107 in which its end forms a nail feeler 129 which is normally maintained in this position by a. torsion spring 125 acting upon the lever 124.

However, instead of being mounted on the lower part of the foot 3, as shown in FIG. 1, the lever 124 is mounted near the upper end of the foot 103 so that the feeler 129 is adapted to engage into the guide channel 107 at the point where the head of a nail 108 is located when this nail is supplied from a magazine 141.

Similarly as in the nailing machine according to FIGS. 1 to 5, the lever 124 likewise forms a locking bolt which, when lever 124 is pivoted to its normal position as shown in FIG. 6, engages into the path of movement of a shoulder 131 on the feeler rod 119. Lever 124 is for this purpose made of a U-shaped cross section, as shown particularly in FIG. 8, and has one arm 142 which forms the nail feeler 129 which is adapted to engage into the guide channel 107, while the lower end of its other arm 143 is provided with a projection which forms the locking bolt 126 which engages the path of movement of shoulder 131 when lever 124 is in its normal position.

In this normal position of lever 124, its upper edge 144 which extends at a right angle to the axis of guide channel 107 engages upon a shoulder 145 on housing 101 which likewise extends at a right angle to the axis of guide channel 107. This has the advantage that, when the guide channel 107 is empty, any impact which is exerted upon the contact feeler 117, for example, at a sudden application of the foot 103 of the nailing machine against a workpiece, will be taken up by the surfaces of edge 144 and shoulder 145 which extend at right angles to the direction of the impact, so that the pivot 120 of lever 124 will be affected as little as possible by such im pacts.

The locking bolt 126 is provided on the arm 143 of lever 124 in such a position that, when a nail 108, as illustrated in FIG. 9, is inserted into the guide channel 107 and the nail feeler 129 is thereby pushed out of the guide channel, lever 124 will be pivoted at such an angle about the axis 120 that the bolt 126 will disengage from the shoulder 131 and thus allow the contact feeler 117 tomove inwardly when the foot 103 is pressed against a workpiece.

Since the manner of operation of the machine according to FIGS. 6 to 9 is otherwise the same as described with reference to the machine according to FIGS. 1 to 5, no further description seems to be necessary.

FIGS. 10 to 13 illustrate a further embodiment of the percussion machine according to the invention in the form of a stapling machine for U-shaped staples. All these parts of this machine which have similar functions as the corresponding parts of the machines according to FIGS. 1 to or 6- to 9 are designated by reference numerals which are increased by 200 over those as applied in FIGS. 1 to 5 or by 100 over those as applied in FIGS. 6 to 9. In view of the preceding description of these functions, it therefore becomes unnecessary to describe them again in detail.

In this stapling machine, the contact feeler 217 which is movable along the foot 203 in a direction parallel to the axis of guide channel 207 is not rigidly secured to the feeler rod 219, which is otherwise similar to the feeler rods of the nailing machines as previously described, but connected thereto by a connecting device which consists of a lever 251. This lever 251 is connected to the lower end of the feeler rod 219 so as to be pivotable about an axis 252 and it is held by means of a torsion spring 253 in the position as illustrated in FIG. 10 in which it engages upon the foot 203 and in which its lower end is located directly adjacent to the upper end 254 of feeler 217. This feeler 217 has a longitudinal slot 255 into which a nose 256 on the foot 203 engages and in which a spring 257 is mounted which is adapted to maintain the feeler 217 in its normal position in which the upper end of its slot 255 engages upon the nose 256 and its upper end 254 is located at a short distance from the lower end of the lever 251. For properly guiding the feeler 217, the foot 203 is provided with a corresponding guiding groove 258.

As illustrated in FIG. 11, guide channel 207 has a long rectangular shape so as to be able to receive the U-shaped staples 208 which are supplied to this channel from a magazine 241 by means of a feed member 259 which is slidable within a feed channel 241 and is acted upon by a spring 261 which presses the staples 208 in the direction toward and into the guide channel 207. The striker 206 has a cross-sectional shape in accordance with that of the channel 207.

The upper part of feed member 259 is provided with a socket bore 262 which extends parallel to the direction of movement of the feed member and terminates into the end surface thereof facing the staples 208 on which the central web 263 of the adjacent staple 208 engages so that the mouth of bore 262 is at least partly covered by the web 263. Axially slidable within this socket bore 262 is a feeler pin 264 which is acted upon by a compression spring 265 which is interposed between the pin and the bottom of bore 262 and is weaker than the spring 261 and therefore presses the pin 264 with a light pressure against the web 263 of the adjacent staple. The wall of guide channel 207 opposite to the magazine 241 is also provided with a bore 266 which is coaxial to and of the same diameter as the socket bore 262 and is at least partly covered by the lever 251.

The feeler pin 264 is adapted to determine whether or not the guide channel 207 contains a staple 208 which is to, be driven by the striker 206 during its next driving stroke into a workpiece. As soon as the striker 206 has driven in the last staple 208 from the magazine 241 and has then been retracted from guide channel 207, the feeler pin 264 will be pushed by the spring 265 transversely through guide channel 207 and through the bore 266 to its most forward end position which is determined by a small pin 268 which projects laterally from the feeler pin 264 and is slidable within a longitudinal slot 267 in the wall of feed member 259 and adapted to abut against the end wall of this slot 267. In this end position of feeler pin 264, its front end abuts against the lever 251 and pivots the same from the position as shown in FIGS. 10 and 12 to the position as shown in FIG. 13, in which the connecting device which is formed by the lever 251 is in its open position. Consequently, although the contact feeler 217 will be pushed upwardly when the stapling machine is applied in this condition against a workpiece, the feeler 217 will then no longer be able to act upon the feeler rod 219 since lever 251 has been pivoted out of the path of travel of the upper end 254 of feeler rod 217. However, even if the machine is operated so that a succession of driving strokes occurs automatically, in which case the foot 203 engages upon the workpiece, as shown in FIG. 12, and the feeler 217 has shifted the rod 219 via the lever 251 to fits uppermost position in which the trigger may be elfectively actuated, lever 251 will be pivoted by the pin 264 to the position as shown in FIG. 13 when the supply of staples in the magazine is exhausted. The feeler rod 219 will then be pushed back or retracted to its lower position as shown in FIGS. 10 and 13 by the action of a suitable spring, not shown. The feeler pin 264 then forms a connecting member which, as long as the feed member 250 engages against a staple 208, will be held against the action of spring 265 in its inactive position relative to the feed member, while when the magazine no longer contains any staples, this feeler pin 264 will pass through the bore 266 and pivot the lever 251 and thereby actuate the connecting device which is formed by this lever.

FIGS. 14 and 15 illustrate a further embodiment of the percussion machine according to the invention in the form of a nailing machine. While those parts in FIGS. 14 and 15 which correspond to the parts as shown in FIGS. 1 to 5 are designated by the same numerals, those parts which are similar in function but of a slightly different construction are designated in FIGS. 14 and 15 by numerals which are increased by 300 over the numerals as applied in FIGS. 1 to 5. In FIGS. 14 and 15, the end portion 309 of the nail feed channel 9 which is located in front of the pivot axis 36 of leaf spring 335 has an inverted U-shaped cross section so as to be open at its lower side. Leaf spring 335 which is pivotable about this axis 36 therefore forms a removable cover for closing the open side 309 of the end portion 309 of the feed channel 9. If leaf spring 335 is pivoted laterally about the axis 36, it is not only possible to pivot the lever 33 out of the slot 32 so as to permit an improperly inserted nail to be removed, but the open side 369 of the end portion 309 of the nail feed channel will also be uncovered so that any causes of interferences may also be removed frorn this end portion 309 of the nail feed channel.

Although our invention has been illustrated and described with reference to the preferred embodiments thereof, we wish to have it understood that it is in no way limited to the details of such embodiments but is capable of numerous modifications within the scope of the appended claims.

Having thus fully disclosed our invention, what we claim is:

1. In a percussion machine for driving individual fas tening elements into workpieces having a housing, a cylinder within said housing, a percussion piston slidable within said cylinder in response to a driving force and a retracting force and a striker rod thereon, actuating means for controlling application of the driving force to said piston, a guide channel on said housing and projecting from said cylinder for guiding said striker rod, and means for feeding one of said fastening elements at a time into said guide channel when said striker rod is retracted so as to be driven by said striker rod during at least one following driving stroke into a workpiece when the free end of said guide channel is applied thereon, the improvement comprising:

first control means for indicating the presence and absence of a fastening element in said guide channel, said first control means including:

a first feeler member movable to at least two positions, said first feeler member in said first of said positions being disposed outside of said guide channel due to the presence of a fastening element within said channel and in a second position extending into said channel when said channel is empty, and resilient means act ing upon said first feeler member for moving the same from said first position to said second position;

second control means operatively connected to said first control means and said actuating means to permit selective actuation of said actuating means to apply driving force to said piston, said second control means being responsive to said first control means such that said piston cannot move in its driving stroke when said first control means indicate the absence of a fastening element in said guide channel, said second control means including:

a control member operatively connected to said first feeler member and being responsive to the position of said first feeler member so as to prevent said second control means from actuat- 10 ing said actuating means when said first feeler member is in its second position, said control member including a second feeler member movably mounted on the walls of said guide channel for movement between a first position where it extends beyond the free end of the guide channel and a second retracted position, said second feeler member being adapted to be moved from its first position to its second position when the free end of said guide channel is pressed against the workpiece;

resilient means acting upon said second feeler member for normally maintaining it in said first position;

and connection means operatively connecting another part of said second control means to said second feeler member, said another part being shiftable between first and second positions and being adapted to act upon said actuating means so as to actuate them to supply driving force to said piston only if said another part is in said second position, said connection means normally moving said another part to said second position when said second feeler member is moved to its second position, said second control means preventing said another part from being moved to its second position when said first feeler member is in its second position, whereby when said end of said second feeler member is pushed by said workpiece to said retracted position said another part of the second control means is shifted to its second position in which it permits said actuating means to be actuated only if said first feeler member is out of its second position.

2. A percussion machine as defined in claim 1, wherein said first feeler member in its second position locks said second feeler member in its first position so as to prevent said second control means from actuating said actuating means when the free end of the guide channel is urged toward the workpiece.

3. A percussion machine as defined in claim 1, wherein said first feeler member in its second position interrupts the connection of said connection means between said second feeler member and said another part so that said another part will not be moved to its second position although the second feeler member is moved to its second position.

4. A percussion machine as defined in claim 1 wherein said connection means comprises:

a connecting element movable by said first feeler member from a normal first position to a second position as said first feeler member moves into its second position, said connecting element operatively connecting said second feeler member to said actuating means when said connecting member is in its first position and operatively disconnecting said second feeler member from said actuating means when said connecting member is in its second position.

5. A percussion machine as defined in claim 1, wherein said feeding means comprise a magazine connected to said guide channel and adapted to hold a plurality of said fastening elements, and a feed element acting upon said fastening elements in said magazine for feeding one of said elements at a time through said aperture into said guide channel, said feed element also forming at least a part of said first control means.

6. A percussion machine as defined in claim 5, wherein said feed element comprises a slide member, pressure means for resiliently pressing said slide member against the last of said fastening elements in said magazine and toward said guide channel, and said slide member being adapted to move through said aperture into said channel when the supply of fastening elements is exhausted, said first feeler member slidably mounted within and relative to said slide member, spring means for likewise pressing said first feeler member against said last fastening element substantially independently of said pressure means, the Wall of said guide channel having at least a recess on its inner side opposite to said first feeler member so as to permit said first feeler member to enter therein and move relative to and beyond said slide member when the supply of fastening elements is exhausted, and means responsive to said relative movement between said feeler member and said slide member for preventing the actuation of said actuating means when said supply is exhausted.

7. A percussion machine as defined in claim 4, wherein said feeding means comprise a magazine connected to said guide channel and adapted to hold a plurality of said fastening elements, and a feed element acting upon said fastening elements in said magazine for feeding one of said elements at a time through said aperture into said guide channel, said feed element comprising a slide member, pressure means for resiliently pressing said slide member against the last of said fastening elements in said magazine and toward said guide channel and adapted to move through said aperture into said channel when the supply of fastening elements is exhausted, said first feeler member being slidably mounted within and relative to said slide member, spring means for likewise pressing said first feeler member against said last fastening element substantially independently of said pressure means, the wall of said guide channel having a second aperture opposite to a part of said first aperture and opposite to said first feeler member so as to permit said first feeler member to pass through both of said apertures when the supply of fastening elements is exhausted and thereby to abut against and move said connecting element into its second position so as to disconnect said second feeler member from said actuating means.

8. A percussion machine as defined in claim 2, furthe comprising:

locking means on said machine for selectively locking said second feeler member in its first position, said locking means being movable between a first position where it does not lock said second feeler member and a second position where it does lock said second feeler member in said first position, said locking means being moved into its second position by said first feeler member when said first feeler member is moved to its second position.

9. A percussion machine as defined in claim 8, wherein said locking means comprises:

a shoulder on said second feeler member;

and a locking member movable by said first feeler member and engaging upon said shoulder when said first feeler member is in its second position.

10. A percussion machine as defined in claim 9, Wherein said locking member is rigidly secured to said first feeler member.

11. A percussion machine as defined in claim 10, wherein said first feeler member and said locking member are integral with each other and together form a U-shaped element pivotably mounted on said guide channel and having two arms and a web connecting said arms, one of said arms forming said first feeler member adapted to engage through said aperture into said guide channel, and the other arm forming said locking member.

12. A percussion machine as defined in claim 111, wherein the end of said aperture in said wall of guide channel nearest said cylinder forms a shoulder, and said arm forming said first feeler member abuts against said last shoulder when said arm forming said locking member is in locking engagement with said shoulder of said second feeler memher. 1'

.13. A percussion machine as defined in claim 1, wherein said first feeler member is adapted to engage into said guide channel substantially at a point where the widest part of said fastening element is normally to be located before being struck by said striker rod.

14. In a percussion machine for driving individual fastening elements into workpieces having a housing, a cylinder in said housing, a percussion piston slidable within said cylinder in response to a driving force and a retracting force and having a striker rod thereon, actuating means for controlling application of said driving force to said piston, a guide channel in said housing and projecting from said cylinder for guiding said striker rod, means for feeding one of said fastening elements at a time into said guide channel when said striker rod is retracted so as to be driven by said striker rod during at least one following driving stroke into a workpiece when the free end of said guide channel is applied thereon, and a feeler member movably mounted on said housing, resilient means for acting upon said feeler member for normally maintaining it in a first position in which one end thereof projects from the free end of said guide channel, while another part of said feeler member cooperates with said actuating means so as to prevent them from being actuated to operate said machine when said feeler member is in its first position, said feeler member being adapted to be moved from its first position to a second position when the free end of the housing part containing said guide channel is pressed against a workpiece, and when said end of said feeler member is pushed by said workpiece to a depressed position said another part thereof is shifted to a position in which it permits said actuating means to :be actuated to operate said machine, the further improvement comprismg:

a stop member mounted on said machine for movement from a first position engaging into the path of travel of said fastening element in said guide channel so as to prevent said element from falling out of said guide channel and a second position out of said path of travel in said guide channel, said stop member being operatively connected to said feeler member so that said stop member will move from said first position to said second position as said feeler member is depressed from its first position to its second position.

15. A percussion machine as defined in claim 14, wherein part of said stop member is in the path of the pointed end of a fastener element in the guide channel when the stop member is provided with a hard-metal insert.

16. A percussion machine as defined in claim 14, Wherein said stop member comprises a lever pivotalbly mounted on the Wall of said guide channel and having a laterally projecting end forming a stop projection adapted to be pivoted into and out of said path of travel of said fastening element.

17. In a percussion machine for driving individual fastening elements into workpieces having a housing, a cylinder in said housing, a percussion piston slidable within said cylinder in response to a driving force and a retracting force and having a striker rod thereon, actuating means for controlling application of said driving force to said piston, a guide channel in said housing and projecting from said cylinder for guiding said striker rod, the wall of said guide channel having a slot extending in the axial direction thereof, and means for feeding one of said fastening elements at a time into said guide channel when said striker rod is retracted so as to be driven by said striker rod during at least one following driving stroke into a workpiece when the free end of said guide channel is applied thereon, the improvement comprising:

a lever pivotably mounted on said housing so as to be movable within said slot relative to said guide channel, said lever having a clamping jaw on the free end thereof for resiliently clamping a fastening element within said guide channel, and a spring acting upon said lever for holding said clamping jaw in its clamping position.

18. A precussion machine as defined in claim 17,

wherein said spring is a leaf spring, and further comprising means for connecting said leaf spring to said housing so as also to be pivotable laterally about an axis extending at a right angle to the pivot axis of said lever so as to permit said spring to be removed from said lever and clamping jaw.

19. A percussion machine as defined in claim 18, further comprising a nail feed channel extending from one side of said housing toward said guide channel and through said slot into said guide channel, the end portion of the wall of said nail feed channel adjacent to said guide channel having an elongated aperture terminating into said guide channel, said leaf spring covering said aperture when in one position and uncovering said aperture when pivoted laterally from said position so as to permit access to the inside of said end portion.

20. A percussion machine as defined in claim 17, further comprising a stop member on said guide channel near the free end thereof for limiting the extent of the pivoting movement of said lever and for thereby preventing said spring from being bent excessively when said striker rod during a driving stroke thereof hits against said clamping jaw and pivots the same out of its clamping position.

21. A percussion machine as defined in claim 14, further comprising control means for indicating the presence and absence of a fastening element in said guide channel, said control means being operatively connected with said feeler member to prevent the actuation of said actuating means to operate said machine when said control means indicate the absence of a fastening element in said guide channel.

22. A percussion machine as defined in claim 21, wherein the wall of said guide channel has an aperture, said control means comprising a second feeler member movable to at least two positions and in a first of said positions being disposed outside of said guide channel due to the presence of a fastening element Within said channel and in a second position extending through said aperture into said channel when said channel is empty, and resilient means acting upon said second feeler member for moving the same from said first position to said second position.

23. A percussion machine as defined in claim 22, further comprising locking means on said machine for selectively locking said first feeler member in its first position, said locking means being movable between a first position where it does not lock said second feeler member and a. second position where it does lock said second feeler member in said first position, said locking means being moved into its second position by said second feeler member when said second feeler member is moved to its second position.

24. A percussion machine as defined in claim 23, wherein said locking means comprises:

a shoulder on said first feeler member; and

a locking member movable by said second feeler member and engaging upon said shoulder when said second feeler member is in its second position.

25. A percussion machine as defined in claim 24, wherein said second feeler member comprises a lever pivotably mounted on the wall of said guide channel and having a laterally projecting end forming said stop member, said lever carrying said locking member which by the movement of said lever due to the insertion of a fastening element into said guide channel is released from said shoulder on said first feeler member so as to permit the latter to be depressed when the free end of said guide channel is pressed against a workpiece, whereupon said actuating means may be actuated to elfect a driving stroke of said percussion piston.

References Cited UNITED STATES PATENTS 518,182 4/1894 Denton 2271 2,180,718 11/1939 Novick 227156X 2,784,406 3/1957 Powers 227-123 2,863,150 12/1958 Yancey 227- 3,141,171 7/1964 Doyle et a1. 227-2 3,198,412 8/1965 Roosa 227-8 3,259,292 7/ 1966 Maynard 227-13OX GRANVILLE Y. CUSTER, JR., Primary Examiner US. Cl. X.R. 227-8,

227 3 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION patent 3,606,128 Dated September 20, 1971 Inventofls) Adolf Cast, et a1.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 20 remove "disadvantageous" and insert-- disadvantageous- Column 8, line 74, remove "250" and insert--259- Column 12, line 45, after "is" insert--in said first position and said last mentioned part of said stop member is--.

Signed and sealed this 28th day of March 1972.

(SEAL) Attest:

EDWARD M.FLEICHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents 

